This invention relates to a bicycle pedal gearshift for enabling a change in speed change of a bicycle by adjusting the ratio of gyration of a pedal.
The driving gear of a bicycle generally includes a front wheel, a pedal connected to the wheel, a rear wheel and a chain connecting the two wheels.
The bicycle may be equipped with various gearshifts. The torque and speed of revolution to turn the pedals, and the rotational speed of the front and rear wheels may be adjusted to be suitable for a user by adjusting the gearshift.
Existing gearshifts may be classified into two types regardless of their various structures.
Some prior art gearshifts have a gear installed on the axle of the rear wheel of a bicycle, a gear cable connecting a chain to the gearshift and an operating mechanism installed on the handle of the bicycle to operate the gear cable.
There is another type gearshift enabling the adjustment of the ratio of gyration of a pedal through the installation of means of adjusting the length of a crank of the bicycle, and various means of adjusting the length are currently suggested.
Existing bicycle pedal gearshifts consist of numerous parts so that their configurations are complicated, causing them to frequently malfunction. The work involved in changing speed is difficult and such designs are not practically applied to and used for a bicycle.